JP7082463B2 - Anchor reinforcement structure and anchor reinforcement method - Google Patents

Description

The present invention relates to, for example, an anchor reinforcing structure and an anchor reinforcing method for anchor bolts for fixing a base plate or the like of a column base.

In order to prevent the structure from collapsing due to an earthquake, the structure such as columns is required to have a seismic strength of a predetermined value or higher. However, old structures may not meet the current seismic standards, as structures constructed before the current seismic standards were not required to have the strict seismic strengths of today. However, it takes time and cost to newly reconstruct all the structures such as columns.

As a method of reinforcing such a structure, for example, there is a method of placing concrete around the column base portion of an existing column to construct a reinforced concrete root winding portion. However, since concrete is constructed around the columns, a lot of construction work such as reinforcing bars and formwork is required, and the size of the columns is increased by the amount of concrete, which hinders the convenience of the building.

On the other hand, structures such as column bases are usually fixed to foundations and ground by anchor bolts (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-104780

If the strength and deformation capacity of the anchor bolts are not sufficient, the structure may tip over due to the anchor bolts breaking at an early stage. Therefore, it may be necessary to reinforce the anchor bolts in order to reinforce the structure. In particular, many anchor bolts used for exposed steel-framed column bases of the old age cause the threaded part to break before the shaft part of the anchor bolt is sufficiently plastically deformed, and the deformation ability of the column base is high. Many are scarce.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an anchor reinforcing structure and an anchor reinforcing method capable of efficiently reinforcing an anchor bolt.

In order to achieve the above-mentioned object, the first invention is an anchor reinforcing structure, wherein an existing anchor bolt for fixing the base plate of the exposed column base, a base plate of the column base fixed by the anchor bolt, and the above-mentioned A fixing plate formed so as to connect both ends in the width direction of the pedestal inside the pedestal with a gap between the shaft member attached to the upper part of the anchor bolt and the base plate. The shaft member is provided, one end of which is joined to the anchor bolt, the fixing plate has a hole through which the shaft member can be inserted, and the shaft member is inserted into the fixing plate. The shaft member protruding from the upper part of the fixing plate is fixed to the upper part of the fixing plate, and the shaft member is plastically deformed with a load smaller than the breaking load of the joint portion between the shaft member and the anchor bolt. At the lower end of the shaft member, a diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed, and a groove is formed on the lower surface side of the diameter-expanded portion. A male screw portion is formed at the upper end portion of the shaft member, the diameter of the shaft portion is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion, and the shaft member and the anchor bolt are opened. It is an anchor reinforced structure characterized in that it is welded first and the welded area of the welded portion is larger than the cross-sectional area of the shaft portion .

The shaft member has a female threaded portion formed at one end, a male threaded portion formed at the other end, and a shaft portion between the female threaded portion and the male threaded portion, and the female threaded portion. Is connected to the anchor bolt, and the male threaded portion may be fixed with a nut on the upper part of the fixing plate in a state where the male threaded portion protrudes from the upper part of the fixing plate.

The shaft member may be composed of the female screw portion, the shaft portion, and the male screw portion as separate bodies, and the shaft portion and the female screw portion may be joined to each other.

The load at which the shaft member starts plastic deformation may be larger than the load at which the threaded portion of the anchor bolt starts plastic deformation and smaller than the load at which the threaded portion breaks.

The load at which the shaft member starts plastic deformation may be smaller than the load at which the threaded portion of the anchor bolt starts plastic deformation.

According to the first invention, the anchor bolt and the fixing plate are joined by the shaft member, and the shaft member starts plastic deformation with a load smaller than the load at which the joint with the anchor bolt breaks, so that in the event of an earthquake or the like. In addition, a sufficient amount of deformation can be secured before the joint with the anchor bolt breaks.

Further, by forming a diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member at the lower end portion of the shaft member and forming a groove on the lower surface side of the diameter-expanded portion, the anchor bolt and the shaft member can be formed. Can be easily welded.

Further, by forming the female threaded portion at one end of the shaft member, the female threaded portion and the threaded portion of the anchor bolt can be easily connected.

Further, in this case, if the female threaded portion member and the shaft portion and the male threaded portion member are separately formed and the shaft member is formed by joining the two members, the shaft member can be easily manufactured.

If the load at which the shaft member starts plastic deformation is larger than the load at which the threaded portion of the anchor bolt starts plastic deformation and smaller than the load at which the threaded portion breaks, high strength and the effect of preventing the anchor from breaking are obtained. It can be compatible.

Further, if the load at which the shaft member starts plastic deformation is smaller than the load at which the threaded portion of the anchor bolt starts plastic deformation, the strength design of the shaft portion is easy.

The second invention is a method for reinforcing an existing anchor for fixing the base plate of the exposed column base, in which a gap is left between the step of removing the nut of the anchor bolt for fixing the base plate of the column base and the base plate . A shaft member is inserted into a hole in a fixing plate formed inside the pedestal to connect both ends in the width direction of the pedestal, and one end of the shaft member is joined to the anchor bolt. It comprises a step of fixing the other end of the shaft member protruding above the fixing plate and the fixing plate on the upper part of the fixing plate, wherein the shaft member is a screw of the anchor bolt. Plastic deformation is started with a load smaller than the load at which the portion breaks, and a diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed at the lower end portion of the shaft member. A groove is formed on the lower surface side of the shaft member, a male screw portion is formed on the upper end portion of the shaft member, and the diameter of the shaft portion is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion. The anchor bolt is welded at the groove, and the welded area of the welded portion is larger than the cross-sectional area of the shaft portion .

According to the second invention, the existing anchor bolt can be easily reinforced.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an anchor reinforcing structure and an anchor reinforcing method capable of efficiently reinforcing an anchor bolt.

The side view which shows the anchor reinforcement structure 1. An enlarged cross-sectional view of the anchor reinforcing structure 1. The figure which shows the other shaft member 13. The figure which shows the existing column base 3. The figure which shows the state which the nut 27 was removed. The figure which shows the state which attaches the shaft member 13 and attaches a nut 17. The figure which shows the state which the column base 3 is displaced. An enlarged sectional view of a portion F in FIG. 7. The figure which shows the relationship between a load and a deformation amount. An enlarged cross-sectional view of the anchor reinforcing structure 1a. An enlarged cross-sectional view of the anchor reinforcing structure 1b.

Hereinafter, the anchor reinforcing structure 1 according to the first embodiment will be described. FIG. 1 is a side view showing the anchor reinforcing structure 1. In the following description, the anchor reinforcing structure 1 shows a reinforcing structure for the anchor bolt 9 that fixes the base plate 7 of the column base 3, but the present invention is not limited to this, as long as it is a structure fixed by an anchor. Applicable.

The column base 3 is constructed on the floor 5 (for example, the foundation). A base plate 7 to which the column base 3 is joined is fixed on the floor 5 with anchor bolts 9. A fixing plate 15 is provided at the lower part of the column base 3 at a predetermined distance from the base plate 7. The fixing plate 15 has a plane substantially parallel to the base plate 7. A shaft member 13 is joined to the upper portion of the anchor bolt 9.

FIG. 2 is an enlarged cross-sectional view taken along the line A of FIG. The shaft member 13 is provided with a female screw portion 19 at one end and a male screw portion 21 at the other end. The shaft portion 23 is located between the female screw portion 19 and the male screw portion 21. The diameter of the shaft portion 23 is smaller than the diameter of the valley portion of the male screw portion 21.

The shaft member 13 may be integrally formed with the female screw portion 19, the male screw portion 21, and the shaft portion 23, but may be separate bodies. For example, as shown in FIG. 3A, the member including the female screw portion 19 and the member including the male screw portion 21 and the shaft portion 23 may be separate bodies.

In this case, the female threaded portion 19a is formed on the opposite side of the female threaded portion 19, and the male threaded portion 21a is formed on the opposite side of the male threaded portion 21. As shown in FIG. 3B, the shaft member 13 is formed by joining the male threaded portion 21a and the female threaded portion 19a.

As shown in FIG. 2, the female threaded portion 19 is connected to the threaded portion 9a of the anchor bolt 9. A hole 25 through which the male screw portion 21 and the shaft portion 23 can be inserted is formed in the fixing plate 15 at a position corresponding to the anchor bolt 9. Therefore, the male screw portion 21 projects upward from the hole 25 of the fixing plate 15. Further, a nut 17 is provided on the male screw portion 21 and is fixed to the upper part of the fixing plate 15.

At this time, a gap is formed between the tip of the shaft member 13 (female threaded portion 19) and the upper surface of the base plate 7. That is, the shaft member 13 does not come into contact with the base plate 7.

The shaft member 13 is made of steel, for example. The shaft member 13 has a male screw portion 21 formed at the end of the rod-shaped material by tapping, and the shaft portion 23 may be reduced in diameter by cutting or the like with respect to the rod-shaped material, for example.

Next, a method of reinforcing the existing column base using the shaft member 13 and the like will be described. FIG. 4 is a diagram showing the existing column base 3. As described above, the column base 3 is installed on the floor 5. The base plate 7 of the column base 3 is fixed to the floor 5 by anchor bolts 9 and nuts 27.

From this state, as shown in FIG. 5, the nut 27 is removed from the anchor bolt 9 (arrow C in the figure). Therefore, the threaded portion 9a of the anchor bolt 9 is in a state of protruding onto the base plate 7.

Next, as shown in FIG. 6, the shaft member 13 is attached to the anchor bolt 9 protruding from the base plate 7. That is, the threaded portion 9a of the anchor bolt 9 and the female threaded portion 19 of the shaft member 13 are joined. At this time, as described above, a gap is formed between the lower end of the shaft member 13 (female threaded portion 19) and the upper surface of the base plate 7.

Further, the male screw portion 21 of the shaft member 13 is inserted into the hole 25 of the fixing plate 15 and protrudes upward of the fixing plate 15. Further, the anchor reinforcing structure 1 is constructed by attaching and fixing the nut 17 to the male screw portion 21 from above the fixing plate 15 (arrow D in the figure). As the nut 17, the nut 27 that has fixed the anchor bolt 9 may be used as it is.

Next, the function of the anchor reinforcing structure 1 will be described. FIG. 7 is a diagram showing a state in which the column base 3 is tilted (arrow E in the figure) during an earthquake, and FIG. 8 is an enlarged cross-sectional view of a portion F in FIG. 7. When the base plate 7 is about to be lifted by an earthquake, tensile stress is applied to the anchor bolt 9 and the shaft member 13.

At this time, since the diameter of the shaft portion 23 of the shaft member 13 is smaller than the diameter of the valley portion of the male screw portion 21, the shaft portion 23 is plastically deformed (elongated deformation) with a smaller load than the male screw portion 21 starts plastic deformation. ) (Arrow H in FIG. 8).

Further, the shaft portion 23 starts plastic deformation with a load smaller than the load at which the threaded portion 9a of the anchor bolt 9 breaks. FIG. 9 is a diagram showing the relationship between the load of each part and the amount of deformation. In the figure, I is a diagram showing the behavior of the anchor bolt 9 (screw portion 9a). The threaded portion 9a starts plastic deformation with a predetermined load (L in the figure). However, since the strength and deformation capacity of the anchor bolt are not sufficient, the threaded portion breaks before the shaft portion of the anchor bolt is sufficiently plastically deformed (M in the figure).

On the other hand, the shaft portion 23 of the shaft member 13 exhibits the behavior as shown by K in the figure, for example. That is, the shaft portion 23 starts plastic deformation with a load smaller than the breaking load of the threaded portion 9a of the anchor bolt 9. Therefore, if the shaft portion 23 is within the range of deformation that can be plastically deformed, the thread portion 9a is not subjected to the load required for the thread portion 9a to break.

As described above, in the present embodiment, the shaft portion 23 is preferentially plastically deformed, so that the anchor bolt 9 can be prevented from breaking. Further, since the load at which the shaft portion 23 starts to undergo plastic deformation is only slightly smaller than the load at which the screw portion 9a breaks, it is possible to prevent the shaft portion 23 from being easily plastically deformed with a small load. Can be done. As described above, it is desirable that the load at which the shaft portion 23 starts plastic deformation is larger than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation and smaller than the load at which the threaded portion 9a breaks.

Here, the inclination allowed for the column base 3 is about 1/30 rad. Therefore, the required elongation amount is preset from the size of the base plate 7 and the inclination thereof. Further, at this time, by setting the gap between the shaft member 13 and the base plate 7 to a required elongation amount or more, the elongation of the shaft portion 23 can be surely allowed.

The shaft portion 23 of the shaft member 13 may behave as shown in J in the figure, for example. That is, the shaft portion 23 may start plastic deformation with a load smaller than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation. Even in this way, the load required for the threaded portion 9a to break is not applied to the threaded portion 9a within the range of the amount of deformation in which the shaft portion 23 can be plastically deformed. Further, it is easy to design the strength of the shaft portion 23 for starting the plastic deformation with a load smaller than the load at which the threaded portion 9a of the anchor bolt 9 starts the plastic deformation.

In this case, the shaft portion 23 starts plastic deformation with a smaller load as compared with the above-mentioned example, but the screw portion 9a of the anchor bolt 9 can be prevented from plastic deformation, so that an earthquake occurs. Later, the repair can be completed only by replacing the shaft member 13.

As described above, according to the present embodiment, the anchor reinforcing structure 1 can be obtained by a simple operation. Therefore, it is easy to reinforce the existing column base 3. Further, since the anchor reinforcing structure 1 can prevent the anchor bolt 9 for fixing the column base 3 from breaking, it is possible to prevent the column base 3 from tipping over.

In addition, after an earthquake, repairs can be easily performed by replacing the shaft member 13.

Further, since the shaft portion 23 of the shaft member 13 is plastically deformed, the design is easier than in the case of controlling the plastic deformation of the threaded portion.

Further, by forming the shaft member 13 by joining two members, one on the male thread portion side and the other on the female thread portion side, it is easy to manufacture each member.

Further, if the plastic deformation starting load of the shaft portion 23 is larger than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation and smaller than the load at which the threaded portion 9a breaks, the anchor bolt 9 is prevented from breaking. , High strength can be achieved at the same time.

Further, if the plastic deformation starting load of the shaft portion 23 is smaller than the load at which the threaded portion 9a of the anchor bolt 9 starts plastic deformation, it is possible to prevent the threaded portion 9a of the anchor bolt 9 from being deformed after the earthquake. ..

Next, the second embodiment will be described. FIG. 10 is a diagram showing an anchor reinforcing structure 1a according to a second embodiment. In the following description, the same reference numerals as those in FIGS. 1 to 8 will be given to the configurations having the same functions as those of the anchor reinforcing structure 1, and duplicate description will be omitted.

The anchor reinforcing structure 1a has almost the same structure as the anchor reinforcing structure 1, except that the shaft member 13a is used. The shaft member 13a is provided with a male screw portion 21 at one end (upper end) and a diameter expansion portion 22 at the other end (lower end) instead of the female screw 19. That is, the intermediate portion between the enlarged diameter portion 22 and the male screw portion 21 becomes the shaft portion 23. The diameter-expanded portion 22 is thicker than the shaft portion 23. Further, the diameter of the shaft portion 23 is smaller than the diameter of the valley portion of the male screw portion 21 and the diameter of the enlarged diameter portion 22.

The enlarged diameter portion 22 at the end of the shaft member 13a is joined to the threaded portion 9a of the anchor bolt 9 by the welded portion 31. That is, the shaft member 13a and the anchor bolt 9 are joined by a structure other than the screw structure. In this case, by providing the groove 29 on the lower surface of the enlarged diameter portion 22, the shaft member 13a and the anchor bolt 9 can be easily welded. The welding area of the welded portion 31 (the cross section perpendicular to the axial direction of the anchor bolt 9 and the cross-sectional area of the joint surface between the weld bead and the anchor bolt 9) is larger than the cross-sectional area of the shaft portion 23.

That is, by making the cross-sectional area of the shaft portion 23 of the shaft member 13 smaller than the cross-sectional area of the valley portion of the male screw portion 21 and the cross-sectional area of the joint portion (welded portion 31) between the shaft member 13 and the anchor bolt 9. The shaft portion 23 can be plastically deformed (stretched and deformed) with a load smaller than that when the male screw portion 21 or the welded portion 31 starts plastic deformation.

As described above, the shaft member 13a and the anchor bolt 9 may be joined by other than joining with screws. Further, as in the anchor reinforcing structure 1b shown in FIG. 11, the shaft member 13a and the fixing plate 15 may be joined at the welded portion 31a. In this case, the male screw portion 21 may not be provided at the upper end portion of the shaft member 13a.

According to the anchor reinforcing structures 1a and 1b according to the second embodiment, the same effect as that of the anchor reinforcing structure 1 according to the first embodiment can be obtained. As described above, the shaft member 13a may be joined by welding if it can be joined to the anchor bolt 9 and the fixing plate 15. Further, using the shaft member 13, the anchor bolt 9 may be joined to the female threaded portion 19 by the threaded portion 9a, and the fixed plate 15 may be joined to the fixed plate 15 by the welded portion 31a. Further, the joining method such as pin joining instead of screw or welding is not particularly limited.

Although the embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention does not depend on the above-described embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs to.

1, 1a, 1b ………… Anchor reinforcement structure 3 ………… Column base 5 ………… Floor 7 ………… Base plate 9 ………… Anchor bolt 9a ………… Threaded parts 13, 13a ………… Shaft member 15 …… … Fixing plate 17 ………… Nuts 19, 19a ………… Female threaded parts 21, 21a ………… Male threaded parts 22 ………… Expanded diameter 23 ………… Shaft 25 ………… Holes 27 ………… Nuts 29 …… … Grooves 31, 31a ……… Welded parts

Claims (4)

It is a reinforcement structure of the anchor,
The existing anchor bolts that fix the base plate of the exposed column base, and
The base plate of the column base fixed with the anchor bolts and
The shaft member attached to the upper part of the anchor bolt and
A fixing plate formed so as to connect both ends in the width direction of the column base inside the column base with a gap between the base plate and the base plate.
Equipped with
One end of the shaft member is joined to the anchor bolt, and the shaft member is joined to the anchor bolt.
The fixing plate has a hole through which the shaft member can be inserted.
With the shaft member inserted through the fixing plate, the shaft member protruding from the upper part of the fixing plate is fixed to the upper part of the fixing plate.
The shaft member starts plastic deformation with a load smaller than the breaking load of the joint portion between the shaft member and the anchor bolt .
A diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed at the lower end portion of the shaft member, and a groove is formed on the lower surface side of the diameter-expanded portion, and the upper end portion of the shaft member is formed. A male screw portion is formed in the portion, and the diameter of the shaft portion is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion.
An anchor reinforcing structure characterized in that the shaft member and the anchor bolt are welded at the groove, and the welded area of the welded portion is larger than the cross-sectional area of the shaft portion . The first aspect of claim 1 , wherein the load at which the shaft member starts plastic deformation is larger than the load at which the threaded portion of the anchor bolt starts plastic deformation and smaller than the load at which the threaded portion breaks. Anchor reinforcement structure. The anchor reinforcing structure according to claim 1 , wherein the load at which the shaft member starts plastic deformation is smaller than the load at which the threaded portion of the anchor bolt starts plastic deformation. It is a method of reinforcing the existing anchor that fixes the base plate of the exposed column base.
The process of removing the nuts of the anchor bolts that fix the base plate of the column base,
A shaft member is inserted into a hole of a fixing plate formed inside the pillar base so as to connect both ends in the width direction of the pillar base with a gap between the base plate and the shaft member, and one of the shaft members is inserted. The process of joining the end of the bolt to the anchor bolt,
A step of fixing the other end of the shaft member protruding above the fixing plate and the fixing plate on the upper part of the fixing plate.
Equipped with
The shaft member starts plastic deformation with a load smaller than the load at which the threaded portion of the anchor bolt breaks .
A diameter-expanded portion thicker than the thickness of the shaft portion in the middle portion of the shaft member is formed at the lower end portion of the shaft member, and a groove is formed on the lower surface side of the diameter-expanded portion, and the upper end portion of the shaft member is formed. A male screw portion is formed in the portion, and the diameter of the shaft portion is smaller than the diameter of the valley portion of the male screw portion and the diameter of the enlarged diameter portion.
An anchor reinforcing method characterized in that the shaft member and the anchor bolt are welded at the groove, and the welded area of the welded portion is larger than the cross-sectional area of the shaft portion .

Images